I did a general search for Thomas Batha, and came up with only a couple on the BMD, and of all the census, so if this is the right man, we seem to be lucky with the surname. Anyway, there is a marriage for Thomas Batha:
Name: Batha, Thomas
Record Type: Marriages
Quarter: June quarter 1880
District: Llanfyllin
County: Denbighshire Montgomeryshire Powys
Volume/ Page: 11b /335
Unfortunately, he is the only one transcribed on the page so far.
(Here are the other entries for Thomas Batha, in case you want to follow them up:
Batha, Thomas 1838 March Deaths Haverfordwest Dyfed Pembrokeshire
Batha, Thomas 1850 December Marriages Oswestry Denbighshire Shropshire
Batha, Thomas 1898 June Deaths Llanfyllin Denbighshire Montgomeryshire
Batha, Thomas 1900 March Deaths Llanfyllin Denbighshire Montgomeryshire )
From 1871:
Civil Parish or Township: Wrexham Regis
Ecclesiastical parish: Wrexham
Town: Wrexham
County/Island: Denbighshire
Source information: RG10/5658
Folio: 103
Page: 34
Household schedule number: 223
Robert Evans abt 1837 Oseresbry, SAL, Head Wrexham Regis DEN
Elizabeth Evans abt 1835 Tetchill, SAL, Wife Wrexham Regis DEN
Mary Evans abt 1859 Monlgomay, MGY, Daughter Wrexham Regis DEN
Robert Evans abt 1862 Welshpool, MGY, Son Wrexham Regis DEN
Susanna Evans abt 1864 Newtown, MGY, Daughter Wrexham Regis DEN
Ann Evans abt 1866 Daughter Wrexham Regis DEN
Jane Evans abt 1870 Daughter Wrexham Regis DEN
So this family with Mary and Ann as daughters could well be the one, especially as they have a strong Montgomery (or Monlgomay) and Shropshire connection. The problem with names like Mary and Ann is that every family at the time had them.
I think your best bet would be to try and confirm the marriage of Mary to Thomas Batha (either looking at the original indexes - there are only 4 names to a page usually). If Mary Evans is there, take a chance and order the marriage cert - a lot at 7 GBP for a bit of a risk. However, that will confirm Mary's place of residence at the time of marriage, her fathers name and occupation. If that ties in with the 1871 census, its looking good.
Just for interest I had a look at the IGI for Thomas Batha, and found 9. Mostly around Carmarthen, but one in Shropshire:
THO. BATHA , Male
Birth:
Christening: 03 NOV 1696 Llanyblodwell, Shropshire, England
Death: 03 FEB 1697
Father: THO. BATHA ; Mother: ELIZ.
Wrong date I know, but may be a progenitor!